Twist-locks are used for securing shipping containers to ships and to each other. Twist-locks are mounted on the bottom and top of shipping containers and thereby multiple containers can be joined in a vertical stack. When shipping containers have been lifted off the ship by a crane the twist-locks must be removed before the containers are taken to another location. Furthermore, when the containers are loaded onto a vessel, twist-locks must be fitted at the wharf to secure containers on board the vessel. Typically, securing or removing twist-locks is via manual handling of the twist-locks from the lower corner casting of a shipping container held approximately 1 to 1.8 meters above the ground by the crane.
This operation is dangerous as the stevedore must manually handle the twist-locks which are quite heavy and work under or adjacent suspended loads in a high traffic area. It is also inefficient as it can take one to three minutes to fit the twist-locks, thereby slowing the crane cycle time. It is also labour cost intensive since two men are often allocated to undertake such a task.
Methods and devices to alleviate this labour intensive task have been proposed including that disclosed in PCT/AU2005/001258, the contents of which are incorporated herein by reference.
An issue with such devices is the removal and storage of the twist-lock devices having been disengaged from the container. Whilst the device of PCT/AU2005/001258 reduces the bottleneck of the process by speeding the removal of the twist-locks, a further bottleneck may be created by the removal of the twist-locks from the device and subsequent storage. Whilst alternatives have been proposed to achieve this, a simpler and cheaper option would provide further advantage to the process.
At the same time, security concerns as to the contents of said containers must be taken into consideration. Without due cause, it is not viable to search containers for, for instance, fissile or radio active material which may represent a security concern. Nevertheless, means for considering whether a container contains such volatile material should be provided. A system to detect fissile material within a container is disclosed in U.S. Pat. No. 6,768,421, the contents of which are incorporated herein by reference. Here a spreader has been adapted to include detection apparatus for detecting radioactive material or potentially radioactive shielding material within the container. This system involves the use of detectors placed within a spreader which is used to lift a container through engagement with the container through twist-lock devices. The accuracy of this system is, however, dependent on the relative movement between the spreader and the container, and movement within a changing environment as the container is shifted from the ship to the wharf. To alleviate the effects of these factors, the spreader would need to engage the container and stay stationary for a sufficient amount of time to record an accurate reading. However, this would potentially result in a bottleneck in the process of handling the container.
It would, therefore, be advantageous if data collection were possible within the overall process so as to reduce the potential for a bottleneck.